The present invention relates to a test circuit for setting the synchronization of a dual ignition system, particularly for a dual magneto system of an aircraft engine.
Dual ignition systems are particularly well suited and advantageous when used for aircraft engines. Aircraft engines are required to achieve maximum possible safety in operation as a primary technical objective. For this reason, systems liable to develop a fault, such as auto-ignition systems, are supplemented by a second parallel system. Aircraft engines, in particular, feature two spark plugs for each cylinder, which plugs are energized by separate ignition systems. It is usual that each of the two ignition systems has a high-tension coil which is coupled to a low-tension coil by a magnetic circuit, the low-tension coil being circuited in parallel to a make/break contact. Actuation of the make/break contacts produce ignition sparks. In a dual magneto system of this kind, both spark plugs must produce an ignition spark in synchronism to each other. For the purpose of setting the synchronization by suitably adjusting the make/break contacts of the dual magneto system, a known relatively complicated electromechanical test circuit is normally used for setting such ignition systems as used in aircraft engines, the known test circuit featuring an electromechanical circuit in the form of a bell generator for producing an alternating current which is applied to the ignition system, in which the indicator elements in the form of jewel lamps indicate the switching condition of the make/break contacts. This known test circuit not only has a relatively high price, this being the reason why this known test circuit finds use as an airport inventory item at best, but is not purchased by any private pilot individually. It also features a non-compact size and high weight, thus making it unsuitable for being included in the flight too kit of a private aircraft. In addition, the operating life and operational safety of the known test circuit have proven to be inadequate.